Percent Change in Pastureland Area, 1982 - 1992

Description

This shaded polygon map shows the percent change in the amount of pastureland area from 1982 to 1992 within each 8 digit hydrologic unit, using 1982 as a base year. The percentages are presented in five categories based on the following divisions: an increase of more than 25%, an increase of 5% to 25%, little change (less than 5% change), a decrease of 5% to 25%, and a decrease of over 25%. Areas with less than 5% pastureland in either 1982 or 1992 are hatched. Areas with 95% or more Federal area are shaded gray. This map replaces map #2308.

Cautions for this Product:
Areas with small amounts of pastureland may have very high rates of change. This map may not be used to determine site-specific information. Data are not collected on Federal land. Data are not shown for areas where pastureland is less than 5% of the total area. Data are not available for Alaska or the Pacific Basin. Data for Puerto Rico and the U.S. Virgin Islands are aggregated by 6-digit hydrologic unit.

Sources

Source:National Resources Inventory, 1997Distributor: USDA-NRCS-RIADReliability:
NRI sample data are generally reliable at the 95% confidence interval for state and certain broad substate area analyses. Generally, analyses that aggregate data points by smaller geographic areas and/or more specific criteria result in fewer data points for each aggregation and therefore less reliable estimates. NRI maps reflect national patterns rather than site- specific information.

Layers

Definitions

Federal land:
A land ownership class designating land that is owned by the Federal Government. It does not include, for example, trust lands administered by the Bureau of Indian Affairs nor Tennessee Valley Authority (TVA) land. No data are collected for any year that land is in this ownership. [NRI-97]

Land cover/use:
A term that includes categories of land cover and categories of land use. Land cover is the vegetation or other kind of material that covers the land surface. Land use is the purpose of human activity on the land; it is usually but not always related to the land cover. The NRI uses the term (land cover/use) to identify the categories that account for all the surface area in the United States [BS-1982; NRI-97]

Native pasture:
A Land Cover/Use included with Pastureland where the climax plant community was forest and is now being used primarily for grazing of native and/or introduced species. [NPM; NRI-87]

Pastureland and Native Pasture:
A Land Cover/Use category of land managed primarily for the production of introduced or native forage plants for livestock grazing. Pastureland may consist of a single species in a pure stand, a grass mixture or a grass-legume mixture. Management usually consists of cultural treatments-fertilization, weed control, reseeding, or renovation and control of grazing. (For the NRI, includes land that has a vegetative cover of grasses, legumes, and/or forbs, regardless of whether or not it is being grazed by livestock.) [NRI-97]